Power control device and power control method

ABSTRACT

To prevent loss of controllability associated with the change in total target power value, and suppress power supply voltage fluctuation. 
     An upper limit value calculation section  20  is provided, which adds a correction value H n  calculated by a correction value calculation section  19  to a sum total Σx n  of target power values x 1n  to x Mn  calculated by a total target power value calculation section  18,  so as to calculate a power upper limit value P LIM  for every load, such that an appropriate power upper limit value P LIM  may be obtained depending on variation of the sum total Σx n  of target power values x 1n  to x Mn .

TECHNICAL FIELD

The present invention relates to a power control device and a powercontrol method for time-divisionally controlling power supplied to aplurality of loads.

BACKGROUND OF THE INVENTION

For example, Patent Documents 1 and 2 below describe a power controldevice that supplies, to a load such as a heater, power proportional toa manipulated signal (target value) output from a PID controller.

This power control device switches on and off the power supplied to theload at time intervals corresponding to an integral multiple a halfcycle of a power source waveform (hereinafter referred to as “unittime”), and supplies to the load the power proportional to themanipulated signal (target value) output from the PID controller bycontrolling a time rate of ON time during which the power is supplied toOFF time during which the power is not supplied.

Below, a mode for controlling the power with this power control deviceis referred to as “time-divisional output control mode”.

In control of the power supplied to N loads (channels), when eachchannel is controlled in the time-divisional output control mode, thenumber of channels powered at one time (the number of channels turned onat one time) in each unit time ranges between 0 (all channels are OFF)and N (all channels are ON).

FIG. 6 is a diagram showing one example of ON/OFF states of channelswhen power control is conducted for 16 channels in the time-divisionaloutput control mode.

As evidenced by FIG. 6, all of the 16 channels may be OFF, or all of the16 channels may be ON. Therefore, the number of channels turned on atone time ranges between 0 and 16.

Further, Patent Documents 3-5 below disclose a power control method forsuppressing a total output power value (sum of consumed power values inone or more channels being powered) to or below a preset power upperlimit value (upper limit value of supplied power values with respect toall of the channels per unit time) in each unit time by limiting thenumber of channels powered at one time in each unit time (hereinafterreferred to as “peak power suppression control”).

PRIOR ART DOCUMENT Patent Document

Patent Document 1: Japanese Patent No. 3022051

Patent Document 2: Japanese Patent No. 3674951

Patent Document 3: Japanese Patent No. 3754974

Patent Document 4: Japanese patent No. 4529153

Patent Document 5: Japanese Patent Application Publication 2

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Since the power control device for conventional peak power suppressioncontrol is configured as stated above, the total output power value fora plurality of channels is suppressed to or below the preset power upperlimit value in each unit time. However, the power upper limit value is apreset fixed value (e.g., a value set by a user in view of power supplycapacity in a factory, an amount of power required for control, etc.),and its setting is not automatically changed.

Therefore, for example, if the power upper limit value is set to beclose to a total value of an amount of power required for stabilizedtemperature control, there is a problem that even if a total targetpower value (sum of target power values of respective channels) is largeas shown in FIG. 8 at Area B (which may be caused by an effect such aselevated temperature, setting change, or disturbance), the total outputpower value is suppressed to or below the power upper limit value, butit takes a long time to reach a target temperature, thereby compromisingcontrollability. Further, due to a delayed disturbance response, thereis a problem with failure of optimal temperature control.

On the other hand, if the total target power value is smaller thannecessary relative to the power upper limit value as shown in FIG. 8 atArea A, there is a problem that a difference between the maximum andminimum values of the total output power values in respective unit timeis large, thereby increasing power supply voltage fluctuation.

The present invention was made to solve the above problems, and isintended to obtain a power control device and a power control methodwhich may prevent loss in controllability associated with a change intotal target power value and suppress the power supply voltagefluctuation.

Means for Solving the Problem

The power control device according to the present invention comprises:

a plurality of switching control means for switching on and off powersupplied to each controlled object at time intervals of predeterminedunit time;

a target power value calculation means for calculating a target powervalue that is a target value of the power supplied to each controlledobject;

an output power value calculation means for calculating an output powervalue that is a value of the power supplied to each controlled object;

a power estimation means for estimating, for each controlled object,from the output power value calculated by the output power valuecalculation means while the power is supplied, a power value when thepower is supplied to the controlled object within the unit time in thenext control cycle;

an intermediate integrated power value calculation means for calculatinga power difference integrated value by repeating an addition of thetarget power value calculated by the target power value calculationmeans and a subtraction of the output power value calculated by theoutput power value calculation means in every control cycle, and addingthe power difference integrated value up to the previous control cycleand the target power value in the next control cycle calculated by thetarget power value calculation means, so as to calculate, for eachcontrolled object, the added value that is the latest intermediateintegrated power value; and

an upper limit value calculation means for calculating an upper limitvalue of supplied power values for all of the controlled objects perunit time, based on a sum total of the target power values of therespective controlled objects calculated by the target power valuecalculation means;

wherein a power control means repeats, with respect to the respectivecontrolled objects in order beginning with a controlled object having alarger intermediate integrated power value calculated by theintermediate integrated power value calculation means, the control toturn on the switching control means for the controlled object if a powersupply condition is satisfied, and to turn off the switching controlmeans for the controlled object if the power supply condition is notsatisfied, thereby controlling ON and OFF of the switching control meansin the next control cycle for all of the controlled objects, and whereinthe power supply condition is that the intermediate integrated powervalue of the controlled object is greater than a predeterminedthreshold, and if the power is to be supplied to the controlled object,a sum total of the power value of the controlled object estimated by thepower estimation means and the power values of other controlled objectsestimated by the power estimation means and determined to be powered inthe next control cycle does not exceed the upper limit value calculatedby the upper limit value calculation means.

The power control device according to the present invention isconfigured such that the upper limit value calculation means adds apredetermined correction value to the sum total of the target powervalues of the respective controlled objects calculated by the targetpower value calculation means, so as to calculate the upper limit valueof the supplied power value.

The power control device according to the present invention isconfigured such that the upper limit value calculation means multipliesa predetermined coefficient and the sum total of the target power valuesof the respective controlled objects calculated by the target powervalue calculation means, so as to calculate the upper limit value of thesupplied power value.

The power control device according to the present invention isconfigured such that the upper limit value calculation means divides asum total of the power difference integrated values of the respectivecontrolled objects calculated by the intermediate integrated power valuecalculation means by a predetermined integral time, and then, adds thedivision result as a correction value to the sum total of the targetpower values of the respective controlled objects calculated by thetarget power value calculation means, so as to calculate the upper limitvalue of the supplied power value.

The power control device according to the present invention isconfigured such that the upper limit value calculation means divides adifference between the sum total of the power difference integratedvalues of the respective controlled objects calculated by theintermediate integrated power value calculation means and a sum total ofthresholds for the respective controlled objects, by a predeterminedintegral time, and then, adds the division result as the correctionvalue to the sum total of the target power values of the respectivecontrolled objects calculated by the target power value calculationmeans, so as to calculate the upper limit value of the supplied powervalue.

The power control device according to the present invention isconfigured such that the correction value added by the upper limit valuecalculation means is within a range from zero value to the maximum valueof power supplied to the respective controlled objects.

The power control device according to the present invention isconfigured such that the upper limit value calculation means adds eitherof the correction value within the range from zero value to the maximumvalue of power supplied to the respective controlled objects or thecorrection value that is the result from the division by thepredetermined integral time, to the sum total of the target power valuesof the respective controlled objects calculated by the target powervalue calculation means, thereby calculating the upper limit value ofthe supplied power value.

A power control method according to the present invention comprises:

a plurality of switching steps in which a plurality of switching controlmeans switch on and off power supplied to respective controlled objectsat time intervals of predetermined unit time;

a target power value calculation step in which a target power valuecalculation means calculates a target power value that is a target valueof the power supplied to each controlled object;

an output power value calculation step in which an output power valuecalculation means calculates an output power value that is a value ofthe power supplied to each controlled object;

a power estimation step in which a power estimation means estimates, foreach controlled object, from the output power value calculated in theoutput power value calculation step while the power is supplied, a powervalue when the power is supplied to the controlled object within theunit time in the next control cycle;

an intermediate integrated power value calculation step in which anintermediate integrated power value calculation means calculates a powerdifference integrated value by repeating an addition of the target powervalue calculated in the target power value calculation step and asubtraction of the output power value calculated in the output powervalue calculation step in every control cycle, and adds the powerdifference integrated value up to the previous control cycle and thetarget power value in the next control cycle calculated in the targetpower value calculation step, so as to calculate, for each controlledobject, the added value that is the latest intermediate integrated powervalue;

an upper limit value calculation step in which an upper limit valuecalculation means calculates an upper limit value of supplied powervalues for all of the controlled objects per unit time, based on a sumtotal of the target power values of the respective controlled objectscalculated in the target power value calculation step; and

a power control step in which a power control means repeats, withrespect to the respective controlled objects in order beginning with acontrolled object having a larger intermediate integrated power valuecalculated in the intermediate integrated power value calculation step,the control to turn on the switching control means for the controlledobject if a power supply condition is satisfied, and to turn off theswitching control means for the controlled object if the power supplycondition is not satisfied, thereby controlling ON and OFF of theswitching control means in the next control cycle for all of thecontrolled objects, wherein the power supply condition is that theintermediate integrated power value of the controlled object is greaterthan a predetermined threshold, and if the power is to be supplied tothe controlled object, a sum total of the power value of the controlledobject estimated in the power estimation step and the power values ofother controlled objects estimated in the power estimation step anddetermined to be powered in the next control cycle does not exceed theupper limit value calculated in the upper limit value calculation step.

Effect of the Invention

The present invention provides an effect in which the upper limit valueof the supplied power value may be appropriately calculated depending ona change in the total target power value, and as a result, loss incontrollability associated with the change in the total target powervalue may be prevented, and the power supply voltage fluctuation may besuppressed.

The present invention also provides an effect of saving time to set theupper limit value by a user.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a power control device according toEmbodiment 1 of the present invention.

FIG. 2 is a flowchart showing processing details by the power controldevice according to Embodiment 1 of the present invention.

FIG. 3 is a flowchart showing processing details by an ON-OFF devicecontrol section 23 of the power control device according to Embodiment 1of the present invention.

FIG. 4 is a schematic diagram showing processing timing of the powercontrol device.

FIG. 5 is a schematic diagram showing examples of control in respectivecontrol cycles in a time-divisional output control mode.

FIG. 6 is a schematic diagram showing one example of ON/OFF states of 16channels when power control is performed on the channels in thetime-divisional output control mode.

FIG. 7 is a schematic diagram showing one example of total powerdifference integrated values when no power upper limit value is set.

FIG. 8 is a schematic diagram showing one example of ON/OFF states ofrespective channels when a fixed power upper limit value is set.

FIG. 9 is a schematic diagram showing one example of total powerdifference integrated values when a fixed power upper limit value isset.

FIG. 10 is a schematic diagram showing one example of ON/OFF states ofrespective channels when a power upper limit value is set by Method A.

FIG. 11 is a schematic diagram showing one example of total powerdifference integrated values when the power upper limit value is set byMethod A.

FIG. 12 is a schematic diagram showing one example of ON/OFF states ofrespective channels when the power upper limit value is set by Method B.

FIG. 13 is a schematic diagram showing one example of total powerdifference integrated values when the power upper limit value is set byMethod B.

FIG. 14 is a schematic diagram showing one example of ON/OFF states ofrespective channels when the power upper limit value is set by Method C.

FIG. 15 is a schematic diagram showing one example of total powerdifference integrated values when the power upper limit value is set byMethod C.

MODE FOR CARRYING OUT THE INVENTION Embodiment 1

FIG. 1 is a block diagram showing the power control device according toEmbodiment 1 of the present invention.

The power control device in FIG. 1 shows an example fortime-divisionally controlling the supply of power to M controlledobjects (M is an integer equal to or greater than 2).

That is, the power control device in FIG. 1 controls ON and OFF of powersupplied to the controlled objects at time intervals corresponding to anintegral multiple a half cycle of a power source waveform (hereinafterreferred to as “unit time”), and supplies to the controlled object thepower proportional to a manipulated signal (target value) output from aPID controller by controlling a time rate of ON time during which thepower is supplied to OFF time during which the power is not supplied.

A cycle for repeating the control to turn on and off the power suppliedto the controlled objects in every unit time is hereinafter referred toas “control cycle”.

In FIG. 1, loads 1-1 to 1-M are controlled objects for the power controldevice, such as a heater.

Regulators 2-1 to 2-M are external devices for the power control device,and output an output target value A_(mn) for the power supplied to theload 1-m to the power control device in every control cycle n.

Incidentally, m is a number for identifying a controlled object amongthe loads 1-1 to 1-M, and m is 1, 2, . . . , M.

Further, n is a number for identifying the control cycle for supplyingthe power to the loads 1-1 to 1-M, and an amount of time in one controlcycle conforms to the above unit time. Incidentally, n is 1, 2, . . . .

In every control cycle n, a target power value calculation section 11inputs a value output from the regulator 2-m at the beginning of thecontrol cycle n as the output target value A_(mn) (for example, apercentage of target power relative to rated power of the load 1-m),multiplies the output target value A_(mn) by a predetermined referencepower value, and then, calculates the multiplication result x_(mn)(=A_(mn)·q_(m)) as a target power value x_(mn) supplied to the load 1-min the control cycle n. Incidentally, the target power value calculationsection 11 constitutes the target power value calculation means.

An output target value input section 12 in the target power valuecalculation section 11 is an interface device for the regulators 2-1 to2-M, and inputs the output target value A_(mn) output from the regulator2-m.

A reference power value storage section 13 is comprised of a memory suchas RAM, and stores a reference power value q_(m) of the load 1-m (e.g.,rated power of the load 1-m).

Target power value calculation processing sections 14-1 to 14-M arecomprised of, for example, multipliers, and in every control cycle n,calculate a target power value x_(mn) of the load 1-m by multiplying theoutput target value A_(mn) input by the output target value inputsection 12 at the beginning of the control cycle n by the referencepower value q_(m) stored in the reference power value storage section13.

Power supply ON-OFF devices 15-1 to 15-M are comprised of, for example,thyristors, and under the instructions of a peak power suppressionoperation section 21, turn on and off the power supplied to the load 1-min every control cycle (unit time). The power supply ON-OFF devices 15-1to 15-M constitute the switching control means.

An output power value calculation section 16 is comprised of, forexample, a semiconductor integrated circuit implementing a CPU, or aone-chip microcomputer, and calculates an output power value q_(mn)tilde that is a value of the power supplied to the load 1-m, during theunit time of the control cycle n. The output power value calculationsection 16 constitutes the output power value calculation means.

In FIG. 1, q_(mn) with a symbol “˜” attached thereon is shown as theoutput power value. However, since this symbol “˜” cannot be attached onq_(mn) in the text of the specification in relation to electronic patentapplication, it is expressed as “q_(mn) tilde” in the text.

In every control cycle n, a value output from the output power valuecalculation section 16 to the peak power suppression operation section21 at the beginning of control cycle n is an output power valueq_(m(n-1)) tilde calculated in the previous control cycle (n−1).

The output power value calculation section 16 may have any configurationas long as it may calculate the output power value q_(mn) tilde in eachunit time of the control cycle n. For example, it may comprise a voltagemeasurement means measuring voltage V_(mn) applied to the load 1-m, acurrent measurement means measuring current I_(mn) flowing through theload 1-m, and a calculation means calculating, from the voltage V_(mn)and current I_(mn), the output power value q_(mn) tilde that is a valueof the power supplied to the load 1-m.

An ON power estimation section 17 is comprised of, for example, asemiconductor integrated circuit implementing a CPU, or a one-chipmicrocomputer. It stores the output power value during the ON timemeasured by the output power value calculation section 16 duringprevious supply of power to the load 1-m, estimates, based on the outputpower value, the power value when the power is supplied to the load 1-m,during the unit time of the control cycle n, and outputs the powerestimated value q_(mon) tilde. The ON power estimation section 17constitutes the power estimation means.

A total target power value calculation section 18 is comprised of, forexample, an adder, and calculates a sum total Σx_(n) of target powervalues x_(1n) to x_(Mn) of the loads 1-1 to 1-M calculated by the targetpower value calculation processing sections 14-1 to 14-M.

A correction value calculation section 19 is comprised of, for example,a semiconductor integrated circuit implementing a CPU, or a one-chipmicrocomputer, and calculates a correction value H_(n) to be added tothe sum total Σx_(n) of target power values x_(1n) to x_(Mn) calculatedby the total target power value calculation section 18.

An upper limit value calculation section 20 is comprised of, forexample, an adder. It adds the correction value H_(n) calculated by thecorrection value calculation section 19 to the sum total Σx_(n) oftarget power values x_(1n) to x_(Mn) calculated by the total targetpower value calculation section 18, thereby calculating an upper limitvalue P_(LIM) of the supplied power values for all of M loads in theunit time of the control cycle n (hereinafter referred to as “powerupper limit value P_(LIM)”).

The total target power value calculation section 18, correction valuecalculation section 19, and upper limit value calculation section 20constitute the upper limit value calculation means.

A peak power suppression operation section 21 is comprised of the ONpower estimation section 17, intermediate integrated power valuecalculation section 22, and ON-OFF device control section 23.

The intermediate integrated power value calculation section 22 iscomprised of subtracters 22 a-1 to 22 a-M, adders 22 b-1 to 22 b-M, andbuffers (Z⁻¹) 22 c-1 to 22 c-M which mean that values are time-shiftedby one control cycle. The intermediate integrated power valuecalculation section 22 subtracts the output power value q_(m(n-1)) tildecalculated by the output power value calculation section 16 from anintermediate integrated power value S_(m(n-1)) hat calculated in theprevious control cycle (n−1), thereby calculating a power differenceintegrated value s_(m(n-1)) (=s_(m(n-1)) hat−q_(m(n-1)) tilde) in theprevious control cycle (n−1); and then adds the power differenceintegrated value S_(m(n-1)) to the target power value x_(mn) calculatedby the target power value calculation processing section 14-m, tocalculate the additional value, i.e., the latest intermediate integratedpower value s_(mn) hat. The intermediate integrated power valuecalculation section 22 constitutes the intermediate integrated powervalue calculation means.

In FIG. 1, S_(mn) with a symbol “̂” attached thereon is shown as theintermediate integrated power value. However, since this symbol “̂”cannot be attached on S_(mn) in the text of the specification inrelation to electronic patent application, it is expressed as “s_(mn)hat”.

The ON-OFF device control section 23 repeats, with respect to the loads1-1 to 1-M in order beginning with the load 1-m having a largerintermediate integrated power value S_(mn) hat calculated by theintermediate integrated power value calculation section 22, the controlto turn on the power supply ON-OFF device 15-m for the load 1-m if thepower supply condition is satisfied and to turn off the power supplyON-OFF device 15-m for the load 1-m if the power supply condition is notsatisfied, thereby controlling ON and OFF of the power supply ON-OFFdevices 15 in the next control cycle for all of the loads, wherein thepower supply condition is that the intermediate integrated power values_(mn) hat of the load 1-m is greater than the predetermined thresholds_(th), and the sum total of the power estimated value q_(mon) tilde ofthe load 1-m estimated by the ON power estimation section 17 and powerestimated values q_(mon) tilde of loads determined to be turned on inthe next control cycle among power estimated values q_(1on) tilde toq_(Mon) tilde of the loads 1-1 to 1-M estimated by the ON powerestimation section 17 does not exceed the power upper limit valueP_(LIM) calculated by the upper limit value calculation section 20. TheON-OFF device control section 23 constitutes the control means.

In the example of FIG. 1, components of the power control device: thetarget power value calculation section 11, power supply ON-OFF devices15-1 to 15-M, output power value calculation section 16, ON powerestimation section 17, total target power value calculation section 18,correction value calculation section 19, upper limit value calculationsection 20, intermediate integrated power value calculation section 22,and ON-OFF device control section 23 are assumed to be composed ofdedicated hardware, respectively. However, the power control device, inwhole or in part, may be composed of a computer.

If the entire power control device is composed of a computer, a programdescriptive of processing details of the target power value calculationsection 11, power supply ON-OFF devices 15-1 to 15-M, output power valuecalculation section 16, ON power estimation section 17, total targetpower value calculation section 18, correction value calculation section19, upper limit value calculation section 20, intermediate integratedpower value calculation section 22, and ON-OFF device control section 23may be stored in computer memory, such that a CPU of the computer mayexecute the program stored in the memory.

FIG. 2 is a flowchart showing processing details by the power controldevice according to Embodiment 1 of the present invention.

FIG. 3 is a flowchart showing processing details by the ON-OFF devicecontrol section 23 of the power control device according to Embodiment 1of the present invention.

The operation is described below.

With a power control device for conventional peak power suppressioncontrol, as stated above, the total output power value for a pluralityof channels is suppressed to or below a preset power upper limit valuein each unit time. However, the power upper limit value is a presetfixed value, and its setting is not automatically changed appropriately.

The power control device of this Embodiment 1 automatically calculatesan appropriate power upper limit value P_(LIM) without manual setting bya user.

This allows for prevention of the loss in controllability associatedwith the change in the total target power value, as well as suppressionof the power supply voltage fluctuation, as described in detail below.

In this Embodiment 1, power control in the n^(th) control cycle isdescribed. FIG. 4 is a schematic diagram showing processing timing ofthe power control device. It shows that processing in the n^(th) controlcycle is performed around a boundary between the (n−1)^(th) controlcycle and the n^(th) control cycle. Described below is the processingfor the n^(th) control cycle conducted at the beginning of the n^(th)control cycle.

The power supply ON-OFF device 15-m (m=1, 2, . . . , M) controls ON andOFF of power supplied to the load 1-m under the instruction of theON-OFF device control section 23 in the peak power suppression operationsection 21, and if the instruction of the ON-OFF device control section23 to the power supply ON-OFF device 15-m for the load 1-m is ON inprocessing in the n^(th) control cycle, the power is supplied to theload 1-m during the n^(th) control cycle.

On the other hand, if the instruction of the ON-OFF device controlsection 23 to the power supply ON-OFF device 15-m for the load 1-m isOFF in processing in the n^(th) control cycle, the power is not suppliedto the load 1-m during the n^(th) control cycle.

In processing in the n^(th) control cycle, the output power valuecalculation section 16 calculates an output power value q_(m(n-1)) tildethat is a value of power supplied to the load 1-m during the unit timeof the control cycle n−1 (Step ST1 in FIG. 2).

That is, if the output power value calculation section 16 comprises, forexample, a voltage measurement means measuring voltage V_(m(n-1))applied to the load 1-m, and a current measurement means measuringcurrent I_(m(n-1)) flowing through the load 1-m, it calculates, at thebeginning of the n^(th) control cycle, the output power value q_(m(n-1))tilde that is a value of power supplied to the load 1-m, based on thevoltage V_(m(n-1)) measured by the voltage measurement means and thecurrent I_(m(n-1)) measured by the current measurement means in the(n−1)^(th) control cycle.

{tilde over (q)}_(m(n-1)) =V _(m(n-1)) ×I _(m(n-1))   (1)

The ON power estimation section 17 stores the output power valuescalculated by the output power value calculation section 16 when thepower is supplied to the loads 1-1 to 1-M (stores the output powervalues for every loads). In the n^(th) control cycle, if the outputpower value q_(m(n-1)) tilde calculated at the beginning of the n^(th)control cycle is not zero (the power was supplied to the load 1-m), itupdates the stored output power value (Step ST2). If the output powervalue q_(m(n-1)) tilde calculated in the (n−1)^(th) control cycle iszero, it does not update the stored output power value.

In the n^(th) control cycle, based on the stored output power value, theON power estimation section 17 estimates, at the beginning of the n^(th)control cycle, a power value for the case of power supply to the load1-m during the unit time of the n^(th) control cycle, and then, outputsthe power estimated value q_(mon) tilde to the ON-OFF device controlsection 23 (Step ST2).

For example, if the power is supplied to the load 1-m in the (n−1)^(th)control cycle, the output power value q_(m(n-1)) tilde calculated at thebeginning of the n^(th) control cycle is output to the ON-OFF devicecontrol section 23 as the power estimated value q_(mon) tilde of theload 1-m.

For example, if the power is not supplied to the load 1-m in in the(n−1)^(th) control cycle but the power is supplied to the load 1-m inthe (n−2)^(th) control cycle, the output power value q_(m(n-2)) tildecalculated at the beginning of the (n−1)^(th) control cycle is output tothe ON-OFF device control section 23 as the power estimated valueq_(mon) tilde of the load 1-m.

In the n^(th) control cycle, upon receiving the output power valueq_(m(n-1)) tilde from the output power value calculation section 16, thesubtracter 22 a-m in the intermediate integrated power value calculationsection 22 subtracts the output power value q_(m(n-1)) tilde from avalue through a buffer (Z⁻¹) 22 c-m meaning that a value is time-shiftedby one control cycle (intermediate integrated power value s_(m(n-1)) hatcalculated in the (n−1)^(th) control cycle), thereby calculating a powerdifference integrated value s_(m(n-1)) up to the (n−1)^(th) controlcycle, and then, outputting the power difference integrated values_(m(n-1)) to the correction value calculation section 19 and adder 22b-m (Step ST3).

s _(m(n-1)) ={tilde over (s)} _(m(n-1)) −{tilde over (q)} _(m(n-1))  (2)

At the beginning of the n^(th) control cycle, the output target valueinput section 12 in the target power value calculation section 11 inputsthe output target value A_(mn) for the power supplied to the load 1-mwhich is output from the regulator 2-m, and outputs the output targetvalue A_(mn) to the target power value calculation processing section14-m.

In the n^(th) control cycle, upon receiving the output target valueA_(mn) from the output target value input section 12, the target powervalue calculation processing section 14-m in the target power valuecalculation section 11 multiplies the reference power value q_(m) storedby the reference power value storage section 13 by the output targetvalue A_(mn), thereby calculating the target power value x_(mn) of theload 1-m, and outputting the target power value x_(mn) to the peak powersuppression operation section 21 and total target power valuecalculation section 18 (Step ST4). While the reference power value q_(m)is assumed to be the rated power of the load 1-m herein, it is notlimited thereto.

x _(mn) =A _(mn) ×q _(m)   (3)

In the n^(th) control cycle, when the subtracter 22 a-m calculates thepower difference integrated value s_(m(n-1)) up to the (n−1)^(th)control cycle, the adder 22 b-m in the intermediate integrated powervalue calculation section 22 adds the power difference integrated values_(m(n-1)) to the target power value x_(mn) calculated by the targetpower value calculation processing sections 14-1 to 14-M, therebycalculating the intermediate integrated power value s_(mn) hat at then^(th) control cycle, and outputting the intermediate integrated powervalue s_(mn) hat to the ON-OFF device control section 23 and buffer(Z⁻¹) 22 c-m (Step ST5). Z⁻¹ in the buffer (Z⁻¹) 22 c-m is an operatorwhich means time-shift of values by one control cycle, and its output isthe intermediate integrated power value s_(m(n-1)) hat calculated in the(n−1)^(th) control cycle.

{tilde over (s)} _(mn) =s _(m(n-1)) +x _(mn)   (4)

In the n^(th) control cycle, when the target power value calculationprocessing sections 14-1 to 14-M calculate the target power valuesx_(1n) to x_(Mn) of the loads 1-1 to 1-M, the total target power valuecalculation section 18 calculates a sum total Σx_(n) of the target powervalues x_(1n) to x_(Mn) (Step ST6).

Σx _(n) =x _(1n) +x _(2n) + . . . +x _(Mn)   (5)

In the n^(th) control cycle, the correction value calculation section 19calculates a correction value H_(n) to be added to the sum total Σx_(n)of the target power values x_(1n) to x_(Mn) calculated by the totaltarget power value calculation section 18 (Step ST7).

Details for calculation of the correction value H_(n) by the correctionvalue calculation section 19 are described below. Given that a valuederived by adding an appropriate correction value H_(n) to the sum totalΣx_(n) of the target power values x_(1n) to x_(Mn) is the power upperlimit value P_(LIM), the difference between the maximum and minimumvalues of the total output power values in every unit time may be small,thereby suppressing the loss in controllability or the power supplyvoltage fluctuation (details for which are described below).

In the n^(th) control cycle, the upper limit value calculation section20 adds the correction value H_(n) calculated by the correction valuecalculation section 19 to the sum total Σx_(n) of the target powervalues x_(1n) to x_(Mn) calculated by the total target power valuecalculation section 18, thereby calculating the power upper limit valueP_(LIM) for M loads 1-1 to 1-M (Step ST8).

P _(LIM) =Σx _(n) +H _(n)   (6)

The ON-OFF device control section 23 in the peak power suppressionoperation section 21 determines whether to turn on or off the powersupply ON-OFF device 15-m in the n^(th) control cycle (Step ST9).

With reference to the flowchart in FIG. 3, the specific processingdetails of the ON-OFF device control section 23 in the peak powersuppression operation section 21 are described below.

The ON-OFF device control section 23 in the peak power suppressionoperation section 21 clears a total power estimated value Σq_(on)described below in each control cycle as an initializing process (StepST21 in FIG. 3).

In the n^(th) control cycle, when the ON-OFF device control section 23receives, from the intermediate integrated power value calculationsection 22, the intermediate integrated power values s_(1n) hat tos_(Mn) hat of the loads 1-1 to 1-M, it compares M intermediateintegrated power values s_(1n) hat to s_(Mn) hat, sorts the Mintermediate integrated power values s_(1n) hat to s_(Mn) hat indescending order, and sets loads 1-m as the controlled objects in order,beginning with the load 1-m having a larger intermediate integratedpower value than the others.

That is, among loads 1-m not yet selected as the controlled objects, theload 1-m having the largest intermediate integrated power value s_(mn)hat is selected as the controlled object (Step ST22).

For example, if the number of loads is three, and an inequality: theintermediate integrated power value s_(1n) hat>intermediate integratedpower value s_(2n) hat>intermediate integrated power value s_(3n) hatholds, “the load 1-1”, “the load 1-2”, and “the load 1-3” are selectedas the controlled objects in this order.

Also, for example, if an inequality: the intermediate integrated powervalue s_(3n) hat>intermediate integrated power value s_(1n)hat>intermediate integrated power value s_(2n) hat holds, “the load1-3”, “the load 1-1”, and “the load 1-2” are selected as the controlledobjects in this order.

When the load 1-m is selected as the controlled object, the ON-OFFdevice control section 23 compares the intermediate integrated powervalue s_(mn) hat of the load 1-m and a predetermined threshold s_(th)(Step ST23). If the intermediate integrated power value s_(mn) hat ofthe load 1-m is larger than the predetermined threshold s_(th), theON-OFF device control section 23 calculates a total power estimatedvalue Σq_(on)′ for ON-OFF determination derived by adding the powerestimated value q_(mon) tilde of the load 1-m to the total powerestimated value Σ_(q) _(on) described below (Step ST24).

Further, when the load 1-m is selected as the controlled object, theON-OFF device control section 23 determines whether the power supplycondition that the intermediate integrated power value s_(mn) hat of theload 1-m is larger than the predetermined threshold s_(th) (Step ST23)and the total power estimated value Σq_(on)′ for ON-OFF determinationdoes not exceed the power upper limit value P_(LIM) calculated by theupper limit value calculation section 20 (Step ST25) is satisfied ornot. That is, it determines whether the following formulae (7) and (8)hold or not.

s_(mn)>s_(th)   (7)

Σq_(on)′≦P_(LIM)   (8)

If the formulae (7) and (8) hold, the above power supply condition issatisfied, and thus, the ON-OFF device control section 23 turns on thepower supply ON-OFF device 15-m for the load 1-m (Step ST26). Thisallows for the power to be supplied to the load 1-m.

If at least one of the formulae (7) and (8) does not hold, the abovepower supply condition is not satisfied, and thus, the ON-OFF devicecontrol section 23 turns off the power supply ON-OFF device 15-m for theload 1-m (Step ST27). Therefore, the power is not supplied to the load1-m.

In the n^(th) control cycle, the ON-OFF device control section 23calculates the sum total of the power estimated values q_(mon) tilde ofthe loads 1-1 to 1-M estimated by the ON power estimation section 17(hereinafter referred to as “total power estimated value Σq_(on)”) (StepST28).

The ON-OFF device control section 23 sets the loads 1-m as thecontrolled objects in order, beginning with the load 1-m having a largerintermediate integrated power value than the others, and repeats theabove control processing (Steps ST22 to ST28) until the control over allof the loads 1-m is completed (Step ST29).

The above is the processing details in the n^(th) control cycle.

In this Embodiment 1, by turning on the power supply ON-OFF device 15-mfor the load 1-m if the power supply condition that the total powerestimated value Σq_(on) does not exceed the power upper limit valueP_(LIM) calculated by the upper limit value calculation section 20 issatisfied, the sum total of the output power values q_(mn) tilde issuppressed not to exceed the power upper limit value P_(LIM) in the unittime of each control cycle. However, unlike the conventionaltime-divisional output control, an appropriate power upper limit valueP_(LIM) (value derived by adding an appropriate correction value H_(n)to the sum total Σx_(n) of the target power values x_(1n) to x_(Mn)) maybe automatically calculated. Thus, the obtained effect is that the lossin controllability associated with the change in total target powervalue may be prevented, and the power supply voltage fluctuation may besuppressed.

The reason why the above effect may be obtained is described below.

First, the principle that an integrated value of the target power valuesx_(mn) conforms to an integrated value of the output power values q_(mn)tilde by the time-divisional output control mode is described.

In the power control device shown in FIG. 1, if the intermediateintegrated power value s_(mn) hat of the load 1-m exceeds the thresholds_(th), thereby satisfying the power supply condition, the power supplyON-OFF device 15-m for the load 1-m is turned on, and the output powervalue q_(mn) tilde is subtracted from the intermediate integrated powervalue s_(mn) hat of the load 1-m. Thus, the power difference integratedvalue s_(mn) of the load 1-m is a finite value between the value derivedby subtracting the output power value q_(mn) tilde from the thresholds_(th) and the threshold s_(th) itself.

The power difference integrated value s_(mn) of the load 1-m may bedivided into the integrated value of target power values x_(mn) and theintegrated value of output power values q_(mn) tilde. If the ON-OFFprocess by the ON-OFF device control section 23 is repeated and then thenumber of repetition n is a sufficiently large value, the integratedvalue of target power values x_(mn) and the integrated value of outputpower values q_(mn) tilde become very large values.

As a result, the power difference integrated value s_(mn) becomes asufficiently small value compared to the integrated value of targetpower values x_(mn) and the integrated value of output power valuesq_(mn) tilde, and thus, the integrated value of target power valuesx_(mn) becomes substantially equal to the integrated value of outputpower values q_(mn) tilde.

Numerical formulae representing that when the number of repetition n isinfinite, the target power value x_(mn) conforms to the output powervalue q_(mn) tilde are as follows:

$\begin{matrix}{{\begin{matrix}{s_{mn} = {\lim\limits_{n->\infty}\left( {{\sum\limits_{i = 1}^{n}{x_{mi} \cdot q}} - {\sum\limits_{i = 1}^{n}{\overset{\sim}{q}}_{mi}}} \right)}} \\{= {{\lim\limits_{n->\infty}\left( {\sum\limits_{i = 1}^{n}{x_{mi} \cdot q}} \right)} - {\lim\limits_{n->\infty}\left( {\sum\limits_{i = 1}^{n}{\overset{\sim}{q}}_{mi}} \right)}}}\end{matrix}\therefore{{s_{th} - {\overset{\sim}{q}}_{mn}} \leq {{\lim\limits_{n->\infty}\left( {\sum\limits_{i = 1}^{n}{x_{mi} \cdot q}} \right)} - {\lim\limits_{n->\infty}\left( {\sum\limits_{i = 1}^{n}{\overset{\sim}{q}}_{mi}} \right)}} \leq s_{th}}}{{And},{{\lim\limits_{n->\infty}\left( {\sum\limits_{i = 1}^{n}{x_{mi} \cdot q}} \right)} = \infty},{{\lim\limits_{n->\infty}\left( {\sum\limits_{i = 1}^{n}{\overset{\sim}{q}}_{mi}} \right)} = {\infty \therefore{{\lim\limits_{n->\infty}\left( {\sum\limits_{i = 1}^{n}{x_{mi} \cdot q}} \right)} \approx {\lim\limits_{n->\infty}\left( {\sum\limits_{i = 1}^{n}{\overset{\sim}{q}}_{mi}} \right)}}}}}} & (9)\end{matrix}$

FIG. 5 is a schematic diagram showing examples of control in respectivecontrol cycles in a time-divisional output control mode. FIG. 5represents the target power values, intermediate integrated powervalues, actual power values (output power values), and power differenceintegrated values in percent, with the assumption that the rated powerof the load is 100%.

For example, if the target power value is set to 30% of the rated powerof the load, it is found that, as shown in FIG. 5( a), the average ofactual power values (output power values) is controlled to be 30%.

Further, if the target power value is set to 55% of the rated power ofthe load, it is found that, as shown in FIG. 5( b), the average ofactual power values (output power values) is controlled to be 55%.

By an operation in the above described time-divisional output controlmode, the difference between the integrated value of target power valuesin respective unit time (hereinafter referred to as “target powerintegrated value”) and the integrated value of output power values inrespective unit time (hereinafter referred to as “output powerintegrated value”) (this difference is hereinafter referred to as “powerdifference integrated value”) is smaller than the predeterminedthreshold, and is larger than the value derived by subtracting, from thethreshold, the power value upon being turned on.

Therefore, when the plurality of loads are controlled in thetime-divisional output control mode, the difference between a totalvalue of the target power integrated values for all of the loads(hereinafter referred to as “total target power integrated value”) and atotal value of the output power integrated values for all of the loads(hereinafter referred to as “total output power integrated value”) (thisdifference is hereinafter referred to as “total power differenceintegrated value”) is smaller than a value derived by adding thethresholds for all of the loads (hereinafter referred to as “totalthreshold”), and is larger than the value derived by subtracting, fromthe total threshold, the total value of power when power is supplied toall of the loads (hereinafter referred to as “total ON power value”).

FIG. 7 is a schematic diagram showing one example of the total powerdifference integrated value when no power upper limit value is set, andshows the above state.

In order to clarify the operating principle, the following explanationrelates to cases in which the threshold is zero. However, the thresholdis not necessarily zero.

In the time-divisional output control mode, the output is either ON orOFF as described above, and the total value of consumed power for the ONchannels (loads) is the total output power value. Thus, the total outputpower values will be discrete values.

On the other hand, the output target values sent from a temperatureregulator, etc. are continuous values calculated through a PIDoperation, etc., and thus, the target power values calculated from theoutput target values are also continuous values. Therefore, total targetpower values which are values derived from adding the target powervalues for all of channels are also continuous values.

For the above reason, the total target power value does not conform tothe total output power value with some exceptions. For example, in FIGS.6 and 8, the total output power value is large or small relative to thetotal target power value in a repetitive manner, but the total outputpower integrated value and total target power integrated value arecontrolled to substantially conform to each other.

Then, in the peak power suppression control mode, the concept of powerupper limit value is introduced, and the total value of output powervalues of channels simultaneously turned on in the same unit time is setto be equal to or below the power upper limit value, thereby controllingthe channels simultaneously turned on. However, in the peak powersuppression control mode, since the time-divisional output control modeis a basic action, as with the time-divisional output control mode, thetotal target power value or total output power value does not conform tothe power upper limit value with some exceptions.

FIG. 8 shows one example of ON/OFF states of respective channels when 16channels as controlled objects are controlled in the peak powersuppression control mode.

In the example of FIG. 8, the total output power value varies, andsituations wherein all of channels are turned off or the power value iscloser to the power upper limit value are found.

Further, the example of FIG. 8 shows that the greater the differencebetween the total target power value and the power upper limit value,the greater the difference between the maximum and minimum values of thetotal output power values in every unit time. At the same time, it showsthat the smaller the difference between the total target power value andpower upper limit value, the smaller the difference between the maximumand minimum values of the total output power values in every unit time.

From this, it is found that in order to lessen the difference betweenthe maximum and minimum values of the total output power values in everyunit time, the power upper limit value should be set as close to thetotal target power value as possible.

However, since the total output power values are discrete values, andthe total output power value is less than the power upper limit valuewith some exceptions, if the power upper limit value excessivelyapproaches the total target power value, the target power integratedvalue cannot be supplied to the load due to the peak power suppressioncontrol.

Area B in FIG. 9 showing the change in the total power differenceintegrated value in Area B in FIG. 8 is one example showing the abovedescribed state. If the power upper limit value excessively approachesthe total target power value, or if the power upper limit value is lessthan the total target power value, the total target power value cannotbe output, and thus, the total power difference integrated valuemonotonically increases based on an operational principle of thetime-divisional output control mode. Area B in FIG. 9 shows that whenthe power upper limit value excessively approaches the total targetpower value, or when the power upper limit value is less than the totaltarget power value, the total power difference integrated valuemonotonically increases.

Based on the above, by setting the power upper limit value as a valuederived by adding an appropriate power value to the total target powervalue, the difference between the maximum and minimum values of thetotal output power values in every unit time may be reduced, so as toachieve the supply of the target power value to the load.

The method for calculating the appropriate power upper limit value isclearly expressed below.

(1) A method in which a correction value is selected depending on apower control condition, such as consumed power or load factor for theloads 1-1 to 1-M, and added to the total target power value, therebycalculating the power upper limit value (hereinafter referred to as“Method A”).

FIG. 10 is a schematic diagram showing one example of ON/OFF states ofrespective channels when the power upper limit value is established byMethod A.

FIG. 11 is a schematic diagram showing one example of total powerdifference integrated values when the power upper limit value isestablished by Method A.

The appropriate power upper limit value varies depending on variation ofrated power of each load 1-m or power target value sent from theregulator 2-m, etc., and thus, it should be any value within apredetermined range depending on the rated power or power target value.

If Method A is used, the correction value calculation section 19selects, as the correction value H_(n), any value within a range between0 and the maximum value of the output power values (maximum value ofpower supplied to the load 1-m).

For example, in the n^(th) control cycle, the output power valueq_(m(n-1)) tilde supplied to the load 1-m may be the correction valueH_(n), or, an average, minimum value, or maximum value of the outputpower values when power is supplied to the load 1-m may be thecorrection value H_(n).

Further, the result derived by multiplying the average, minimum value,or maximum value by an appropriate coefficient may be the correctionvalue H_(n).

When the correction value calculation section 19 selects the correctionvalue H_(n), the upper limit value calculation section 20 adds thecorrection value H_(n) to the total target power value (sum total Σx_(n)of target power values x_(1n) to x_(Mn) calculated by the total targetpower value calculation section 18) as described above, therebycalculating the power upper limit value P_(LIM) for the supplied powervalue (refer to the above formula (6)).

This causes the power upper limit value P_(LIM) to be within a rangebetween the total target power value and a value derived from totaltarget power value+correction value H_(n).

In power control, since the supply of the target power value x_(mn) tothe load 1-m should have priority, the power upper limit value P_(LIM)is desirably a sufficiently large value.

This provides a merit that while there is room for improvement in thatthe difference between the maximum and minimum values of the totaloutput power values in every unit time may be further reduced, the powerupper limit value P_(LIM) established by Method A has a margin relativeto the limit value (maximum value of the total output power values), andthus, delay of the output power value q_(mn) tilde relative to thetarget power value x_(mn) may be reduced to reduce an impact ontemperature control.

As shown in FIG. 10, since the power upper limit value P_(LIM)established by Method A varies depending on change in the total targetpower value, variation in the total output power value in every unittime becomes small, and as a result, the maximum value of the totaloutput power values is also small.

For a fixed power upper limit value, as shown in Area B of FIG. 8, thereis a problem that when the total target power value is equal to orgreater than the power upper limit value, the total target power valuecannot be output. However, if the power upper limit value P_(LIM) isestablished by Method A, since it varies depending on change in thetotal target power value, the total target power value is not equal toor greater than the power upper limit value P_(LIM) such that the aboveproblem may be avoided.

Here, the power upper limit value P_(LIM) is calculated by selecting theappropriate correction value H_(n) and adding the correction value H_(n)to the total target power value. However, by selecting a predeterminedcoefficient as the correction value H_(n), and multiplying thecoefficient by the total target power value, a power upper limit valueP_(LIM)′ corresponding to the above power upper limit value P_(LIM)(P_(LIM)≈P_(LIM)′) may be calculated.

(2) A method in which the difference between the sum total of powerdifference integrated values of the loads 1-1 to 1-M and the sum totalof thresholds for the loads 1-1 to 1-M is multiplied by a predeterminedcoefficient, and the multiplication result is added as the correctionvalue to the total target power value, thereby calculating the powerupper limit value (hereinafter referred to as “Method B”).

FIG. 12 is a schematic diagram showing one example of ON/OFF states ofrespective channels when the power upper limit value is established byMethod B.

FIG. 13 is a schematic diagram showing one example of total powerdifference integrated values when the power upper limit value isestablished by Method B.

The sum total of thresholds s_(th) for the loads 1-1 to 1-M ishereinafter referred to as “total threshold”. In order to simplify theexplanation here, the thresholds s_(th) for the loads 1-1 to 1-M arezero.

In this case, Method B is a method in which “a predetermined coefficientis multiplied by the sum total of the power difference integrated valuesof the loads 1-1 to 1-M, and the multiplied result is added as thecorrection value H_(n) to the total target power value, therebycalculating the power upper limit value P_(LIM”.)

Incidentally, a reciprocal of the above predetermined coefficientcorresponds to a value usually referred to as integral time in PIDcontrol. Thus, multiplication of the predetermined coefficient issynonymous with division by the integral time.

According to the time-divisional power control protocol, in the n^(th)control cycle, the power difference integrated value s_(m(n-1)) up tothe (n−1)^(th) control cycle calculated by the subtracter 22 a-m in theintermediate integrated power value calculation section 22 is alwayssmaller than the threshold s_(th) (here, the threshold s_(th) is zero,and thus, it is less than zero).

FIG. 9 is a schematic diagram showing one example of total powerdifference integrated values when a fixed power upper limit value isset, and Area A in FIG. 9 corresponds to the above state.

On the other hand, if no power is supplied to the load 1-m by a peakpower suppression function, the power difference integrated values_(m(n-1)) up to the (n−1)^(th) control cycle increases. Area B in FIG.9 corresponds to the above states.

Thus, if the power upper limit value P_(LIM) is calculated based onMethod B by dividing the sum total Σs_((n-1)) of power differenceintegrated values s_(1(n-1)) to s_(M(n-1)) of the loads 1-1 to 1-M bythe integral time, and adding the division result as the correctionvalue H_(n) to the sum total Σx_(n) of target power values x_(1n) tox_(Mn), the following occurs.

Under the circumstances in which the power upper limit value P_(LIM) issmall, and the total output power value (sum total of output powervalues q_(1(n-1)) tilde to q_(m(n-1)) tilde of the loads 1-1 to 1-Mcalculated by the output power value calculation section 16) is small,the total power difference integrated value (sum total of powerdifference integrated values s_(1(n-1)) to s_(m(n-1))) is large, andthus, the power upper limit value P_(LIM) becomes progressively larger,and thereby, over the course of time, provides a situation foroutputting the target power value.

On the other hand, under the circumstances in which the power upperlimit value P_(LIM) is large, and sufficient total output power valuemay be output, the total power difference integrated value is a negativevalue (a value less than the total threshold), and thus, the power upperlimit value P_(LIM) becomes progressively smaller, and thereby, over thecourse of time, gets rid of the unnecessarily large power upper limitvalue P_(LIM).

Based on the above, if the power upper limit value is established byMethod B, an equilibrium state is provided with the power upper limitvalue P_(LIM) being at an appropriate value, as shown in FIG. 12.

(3) A method for using Method A and Method B together (hereinafterreferred to as “Method C”).

FIG. 14 is a schematic diagram showing one example of ON/OFF states ofrespective channels when the power upper limit value is established byMethod C.

FIG. 15 is a schematic diagram showing one example of total powerdifference integrated values when the power upper limit value isestablished by Method C.

When Method C is used, the correction value calculation section 19outputs either the correction value H_(n) established by Method A (anyvalue within the range between 0 and the maximum value of output powervalues), or the correction value H_(n) established by Method B (divisionresult by the integral time), to the upper limit value calculationsection 20.

Upon receiving the correction value H_(n) from the correction valuecalculation section 19, the upper limit value calculation section 20adds the correction value H_(n) to the total target power value (sumtotal Σx_(n) of target power values x_(1n) to x_(Mn) calculated by thetotal target power value calculation section 18), thereby calculatingthe power upper limit value P_(LIM) of the supplied power value (referto the above formula (6)).

When Method C is used, as shown in FIG. 14, the total power differenceintegrated value may be a value around zero (total threshold).

Thus, as shown in FIG. 15, this method may improve consistency betweenthe total target power integrated value and the total output powerintegrated value, compared to the use of Method A or Method B alone.

As evidenced from the above, according to this Embodiment 1, the upperlimit value calculation section 20 is provided which adds the correctionvalue H_(n) calculated by the correction value calculation section 19 tothe sum total Σx_(n) of target power values x_(1n) to x_(Mn) calculatedby the total target power value calculation section 18 so as tocalculate the power upper limit value P_(LIM) for all of the loads; andthe ON-OFF device control section 23 is configured to turn on the powersupply ON-OFF device 15-m for the load 1-m if the power supply conditionis satisfied, and to turn off the power supply ON-OFF device 15-m forthe load 1-m if the power supply condition is not satisfied, beginningwith the load 1-m among the loads 1-1 to 1-M, having a largerintermediate integrated power value S_(mn) hat calculated by theintermediate integrated power value calculation section 22, wherein thepower supply condition is that the intermediate integrated power values_(mn) hat of the load 1-m is larger than the predetermined thresholds_(th), and the sum total of power estimated value q_(mon) tilde of theload 1-m estimated by the ON power estimation section 17 and the powerestimated values q_(mon) tilde of the loads determined to be turned onin the next control cycle among the estimated power values q_(1on) tildeto q_(Mon) tilde of the loads 1-1 to 1-M estimated by the ON powerestimation section 17 does not exceed the power upper limit valueP_(LIM) calculated by the upper limit value calculation section 20. Thisprovides an effect in which loss in controllability associated with thechange in total target power value may be prevented and the power supplyvoltage fluctuation may be suppressed.

It also provides an effect of saving time to establish the power upperlimit value P_(LIM) by a user.

EXPLANATIONS OF NUMERALS

-   1-1 to 1-M: loads-   2-1 to 2-M: regulators-   11: target power value calculation section (target power value    calculation means)-   12: output target value input section-   13: reference power value storage section-   14-1 to 14-M: target power value calculation sections-   15-1 to 15-M: power supply ON-OFF devices (switching control means)-   16: output power value calculation section (output power value    calculation means)-   17: ON power estimation section (power estimation means)-   18: total target power value calculation section (upper limit value    calculation means)-   19: correction value calculation section (upper limit value    calculation means)-   20: upper limit value calculation section (upper limit value    calculation means)-   21: peak power suppression operation section-   22: intermediate integrated power value calculation section    (intermediate integrated power value calculation means)-   22 a-1 to 22 a-M: subtracters-   22 b-1 to 22 b-M: adders-   22 c-1 to 22 c-M: buffers (Z⁻¹)-   23: ON-OFF device control section (controlling means)

1. A power control device comprising: a plurality of switching controlmeans for switching on and off power supplied to each controlled objectat time intervals of predetermined unit time; a target power valuecalculation means for calculating a target power value that is a targetvalue of the power supplied to each controlled object; an output powervalue calculation means for calculating an output power value that is avalue of the power supplied to each controlled object; a powerestimation means for estimating, for each controlled object, from theoutput power value calculated by the output power value calculationmeans while the power is supplied, a power value when the power issupplied to the controlled object within the unit time in the nextcontrol cycle; an upper limit value calculation means for calculating anupper limit value of supplied power values for all of the controlledobjects per unit time, based on a sum total of the target power valuesof the respective controlled objects calculated by the target powervalue calculation means; an intermediate integrated power valuecalculation means for calculating a power difference integrated value byrepeating an addition of the target power value calculated by the targetpower value calculation means and a subtraction of the output powervalue calculated by the output power value calculation means in everycontrol cycle, and adding a power difference integrated value up to theprevious control cycle and the target power value in the next controlcycle calculated by the target power value calculation means, so as tocalculate, for each controlled object, the added value that is thelatest intermediate integrated power value; and a power control meanswhich repeats, with respect to the respective controlled objects inorder beginning with a controlled object having a larger intermediateintegrated power value calculated by the intermediate integrated powervalue calculation means, the control to turn on the switching controlmeans for the controlled object if a power supply condition issatisfied, and to turn off the switching control means for thecontrolled object if the power supply condition is not satisfied,thereby controlling ON and OFF of the switching control means in thenext control cycle for all of the controlled objects, wherein the powersupply condition is that the intermediate integrated power value of thecontrolled object is greater than a predetermined threshold, and if thepower is to be supplied to the controlled object, a sum total of thepower value of the controlled object estimated by the power estimationmeans and the power values of other controlled objects estimated by thepower estimation means and determined to be powered in the next controlcycle does not exceed the upper limit value calculated by the upperlimit value calculation means.
 2. The power control device according toclaim 1, characterized in that the upper limit value calculation meansadds a predetermined correction value to the sum total of the targetpower values of the respective controlled objects calculated by thetarget power value calculation means, so as to calculate the upper limitvalue of the supplied power value.
 3. The power control device accordingto claim 1, characterized in that the upper limit value calculationmeans multiplies a predetermined coefficient and the sum total of thetarget power values of the respective controlled objects calculated bythe target power value calculation means, so as to calculate the upperlimit value of the supplied power value.
 4. The power control deviceaccording to claim 1, characterized in that the upper limit valuecalculation means divides a sum total of the power difference integratedvalues of the respective controlled objects calculated by theintermediate integrated power value calculation means by a predeterminedintegral time, and then, adds the division result as a correction valueto the sum total of the target power values of the respective controlledobjects calculated by the target power value calculation means, so as tocalculate the upper limit value of the supplied power value.
 5. Thepower control device according to claim 1, characterized in that theupper limit value calculation means divides a difference between the sumtotal of the power difference integrated values of the respectivecontrolled objects calculated by the intermediate integrated power valuecalculation means and a sum total of thresholds for the respectivecontrolled objects, by a predetermined integral time, and then, adds thedivision result as a correction value to the sum total of the targetpower values of the respective controlled objects calculated by thetarget power value calculation means, so as to calculate the upper limitvalue of the supplied power value.
 6. The power control device accordingto claim 2, characterized in that the correction value added by theupper limit value calculation means is within a range from zero value tothe maximum value of power supplied to the respective controlledobjects.
 7. The power control device according to claim 4, characterizedin that the upper limit value calculation means adds either of thecorrection value within the range from zero value to the maximum valueof power supplied to the respective controlled objects or the correctionvalue that is the result from the division by the predetermined integraltime, to the sum total of the target power values of the respectivecontrolled objects calculated by the target power value calculationmeans, thereby calculating the upper limit value of the supplied powervalue.
 8. The power control device according to claim 5, characterizedin that the upper limit value calculation means adds either of thecorrection value within the range from zero value to the maximum valueof power supplied to the respective controlled objects or the correctionvalue that is the result from the division by the predetermined integraltime, to the sum total of the target power values of the respectivecontrolled objects calculated by the target power value calculationmeans, thereby calculating the upper limit value of the supplied powervalue.
 9. A power control method comprising: a plurality of switchingsteps in which a plurality of switching control means switch on and offpower supplied to respective controlled objects at time intervals ofpredetermined unit time; a target power value calculation step in whicha target power value calculation means calculates a target power valuethat is a target value of the power supplied to each controlled object;an output power value calculation step in which an output power valuecalculation means calculates an output power value that is a value ofthe power supplied to each controlled object; a power estimation step inwhich a power estimation means estimates, for each controlled object,from the output power value calculated in the output power valuecalculation step while the power is supplied, a power value when thepower is supplied to the controlled object within the unit time in thenext control cycle; an upper limit value calculation step in which anupper limit value calculation means calculates an upper limit value ofsupplied power values for all of the controlled objects per unit time,based on a sum total of the target power values of the respectivecontrolled objects calculated in the target power value calculationstep; an intermediate integrated power value calculation step in whichan intermediate integrated power value calculation means calculates apower difference integrated value by repeating an addition of the targetpower value calculated in the target power value calculation step and asubtraction of the output power value calculated in the output powervalue calculation step in every control cycle, and adds the powerdifference integrated value up to the previous control cycle and thetarget power value in the next control cycle calculated in the targetpower value calculation step, so as to calculate, for each controlledobject, the added value that is the latest intermediate integrated powervalue; and a power control step in which a power control means repeats,with respect to the respective controlled objects in order beginningwith a controlled object having a larger intermediate integrated powervalue calculated in the intermediate integrated power value calculationstep, the control to turn on the switching control means for thecontrolled object if a power supply condition is satisfied, and to turnoff the switching control means for the controlled object if the powersupply condition is not satisfied, thereby controlling ON and OFF of theswitching control means in the next control cycle for all of thecontrolled objects, wherein the power supply condition is that theintermediate integrated power value of the controlled object is greaterthan a predetermined threshold, and if the power is to be supplied tothe controlled object, a sum total of the power value of the controlledobject estimated in the power estimation step and the power values ofother controlled objects estimated in the power estimation step anddetermined to be powered in the next control cycle does not exceed theupper limit value calculated in the upper limit value calculation step.